10.3 Conclusion

The
vast majority of functionality in VS.NET is implemented through
packages. The Visual Studio Integration Program enables you to write
your own packages, which means that your project types, editors, and
designers effectively become peers of the built-in project types.
VS.NET extensions built as packages are first-class citizens within
the IDE. The main role of the IDE itself is to be a shell that hosts
packages and enables them to exchange services. For more information
on how to obtain the VSIP SDK, see http://msdn.microsoft.com/vstudio/vsip/vsi/default.asp.